According to Tullamore-based Teagasc tillage advisor, John Kelly, winter barley crops should be producing between four and five tillers at the present time. He said:
“This is putting us on course to achieve the 1,000 to 1 200 shoots per m³ target.
Early March is perfect timing for the first split of nitrogen. Crops that received no P and K back in the autumn should receive both these nutrients with the first nitrogen split.
Kelly spoke at the recent Teagasc spring agronomy webinar, from a field that had previously yielded 3.5t/ac. It has a P (phosphorus) index of 3.0; a K (potassium) index of 2.0 and a soil pH value of 7.0.
He continued:
The crop will require 180kg of nitrogen (N) per hectare; 32kg of phosphorous and 100kg of potassium.
Kelly went on to confirm that the crop will receive three spits of nitrogen. The first will be applied now and will comprise: 3.25 bags of 10:8:25 plus sulphur; the second, sown at growth stage 30, will comprise 72 units of nitrogen with the final split, sown at growth stage 31, containing 32 units of nitrogen.
Growth regulators
Joint Teagasc / Boortmalt advisor Eoin Lyons also addressed the webinar.
If target shoot numbers have not been reached, then the issue of tiller survival must be factored in when it comes to applying growth regulators.
In such instances they should be applied before the crops have reached growth stage 30. A follow-up application will be required when the crop is between growth stages 31 and 32.
Lyons continued:
“In crops where the risk of lodging is high for example, if the barley follows a crops of beans, a second growth regulator application should be considered between growth stages 32 and 39 in order to shorten the straw.
When applying growth regulators during the month of March, it is important to take account of the large temperature swings that can take place between day and night during this period.
“Extremes in temperature of this nature can create high levels of stress within a winter barley crop.
“Growth regulator applications will only add to this stress. So again this should be factored in over the coming weeks,” he concluded.